1. Technical Field of the Invention
The present invention relates generally to flow control devices and, more particularly, to a pintle-type control valve which includes a uniquely configured seat ring outfitted with flow passages adapted to operatively interact with a valve plug in a manner providing prescribed pressure reduction characteristics in a fluid flowing through the flow passages.
2. Description of the Related Art
There is currently known in the prior art a type of control valve commonly referred to as a pintle valve wherein the short extension of a needle-valve tip is used to facilitate the control of fluid through the valve. An exemplary pintle-type fluid flow control device or control valve is described with particularity in Applicant's U.S. Pat. No. 5,803,119 entitled FLUID FLOW CONTROL DEVICE issued Sep. 8, 1998.
In one embodiment of the control valve described in the '119 Patent, a cylindrical plug is moveable axially within a complimentary cylinder. The plug includes a fluid flow path extending axially therein. As the plug is moved axially relative to the cylinder, the area of path entry available for fluid flow and the length of the fluid flow path is varied. As a result, as the plug moves further out of the cylinder, a corresponding increase in fluid flow is obtained in the control valve.
The flow control device or control valve constructed in accordance with the present invention represents an improvement over the control valve described in the '119 Patent by virtue of its inclusion of more intricate and complex flow passages which are formed in the seat ring of the control valve, rather than in the reciprocally moveable plug thereof. The increased intricacy/complexity of the flow passages within the control valve of the present invention provides for a better flow range/rangeability therethrough. These, as well as other features and advantages of the present invention, will be described in more detail below.